1. Field of the Invention
This invention relates generally to an apparatus for injecting fertilizer into the soil below the surface thereof. More particularly, the invention relates to a subterraneous treatment apparatus which is insertable into the ground and is capable of injecting controlled amounts of fertilizer into the soil adjacent the root system of plants.
2. Description of the Prior Art
The prior art has disclosed many appropriate devices capable of supplying beneficial materials such as fertilizers and other chemicals to the roots of various plants. One such device is described in U.S. Pat. No. 2,242,789, issued May 20, 1941 to McFee. This patent discloses an apparatus for injecting pulverized or granular fertilizers into the soil comprising a cylindrical closed container for the fertilizer, a tube having one end formed for insertion into the ground and the other end open and extending through the bottom of the closed container. The apparatus is designed for connection to a hose and is provided with an inlet valve, a by-pass valve and a valve to control the flow of fluid through the tube. The fertilizer held in the closed container is taken in suspension by a stream of water which is then carried into the soil below the surface thereof. Similar devices for underground fertilization of plant roots in which a stream of water is admitted to the container of fertilizer prior to being dispensed below the surface of the soil are described in U.S. Pat. Nos. 3,618,539 and 4,432,291, for example.
The prior art further discloses devices for aerating soil and injecting fertilizer and water to the loosened dirt around the roots of trees and shrubs. U.S. Pat. No. 4,682,550 issued July 28, 1987 to Joy discloses a hand-held device capable of effectively breaking up soil around the roots of trees and plants with compressed air, injecting granular fertilizer into the loosened soil, and injecting water therein to dissolve the fertilizer, all in a single operation. The root treatment device described by Joy includes a cylindrical housing tapered at its lower end and having an open reservior which contains granular fertilizer at the upper portion. An inner tube extends concentrally through the housing and a circular ground plate is attached at the lower portion of the housing. An air inlet pipe is attached to the upper end of the outer cylindrical housing and a water inlet pipe connects to the inner tube. Despite the recognition by the patentee of the advantages of providing an apparatus that combines aeration and underground fertilization in a single operation, the device described in U.S. Pat. No. 4,682,550 is poorly constructed and inefficient. This patented device requires an auxiliary piece of equipment, such as a pneumatic drill, since no structural means are provided for inserting the device into the ground. Also, the repetitive lifting and falling action of the device during the aeration operation would result in spillage of the granular fertilizer from the open reservior. Moreover, the prior art apparatus would have to be substantially modified to accommodate liquid fertilizer or other fluid treatment material. In addition, the granular fertilizer employed by Joy is injected in indeterminate amounts as a solid which would result in uneven distribution and varying concentrations around the plant roots.